Thin flexible glass has advantages over plastic in the areas of transparency, hermeticity, dimensional stability, surface smoothness, resistance to scratching and wrinkling. The main challenge with flexible glass is that if there is a small flaw in its surface or at an edge it could serve as a source of origin for a crack, which could cause breakage. Glass has high compressive strength but has low tensile strength in the presence of defects.
It is known that optical fiber made of glass can have high tensile strength as long as the surface of the glass is coated and protected immediately after the fiber is made. Optical fiber is made by pulling on the end of a thicker rod of glass as it is heated, pulling it down to a very small diameter, on the order of 125 microns, coating it with layers, and then winding it on a spool. A critical part of this process, though, is coating the fiber immediately after it is formed before anything else is done with it. The breakage strength of optical fiber drops drastically upon simple exposure to the atmosphere. Oxygen and moisture can attack the glass surface and create microscopic defects that can initiate a propagating crack.
One method for manufacturing glass is by the draw process. Two examples of draw are redraw and fusion draw. With redraw, such as is used in making optical fiber, there is a starting piece of glass that is in a shape that is similar to what is desired in a product but is larger in cross sectional area. The end is heated and it is pulled like candy taffy in a controlled way and extended to a vastly longer dimension. In contrast, fusion draw is usually used to make sheets of glass by overflowing a trough that looks like a rain gutter. The glass overflows on both sides and merges together to form a sheet of glass below the trough as it is pulled through. The glass can be pulled from the bottom of the trough resulting in very thin glass that can then be bent and wound on a spool.
A number of coatings can serve to protect the surface of glass to prevent crack initiation, which could then prevent crack propagation. Of particular interest are inorganic coatings that FIG protect the glass while still allowing the glass to be used in processes at high temperature where plastics might fail.